Method and apparatus for reducing strip



April 1968 J. A. CAMPBELL 3,377,830

METHOD AND APPARATUS FOR REDUCING STRIP Filed June 18, 1965 2 Sheets-Sheet 1.

trot Control Control 62C ontro on t tro/ Contr 680 636 i 54 5/0 490 comm/I ontro tro/ Contr Control 60C Control Cont INVENTOR. JOHN A. CAMPBEL L Attorney April 16, 1968 J. A CAMPBELL 3,377,830

METHOD AND APPARATUS FOR REDUCING STRIP Filed June 18, 1965 2 Sheets-Sheet 2 fi 24 arz aa 2 34%;? I I Flt-L 5- INVENTOR. JOHN A. CAMPBEL L Attorney a -l-IIZZ United States Patent v 3,377,830 METHOD AND APPARATUS FOR REDUCING STRIP John A. Campbell, Lower Makefield Township, Bucks County, Pa, assignor to United States Steel Corporation, a corporation of Delaware Filed June 18, 1965, Ser. No. 465,115 6 Claims. (Cl. 72-205) ABSTRACT OF THE DISCLOSURE A method of reducing the thickness of a strip by passing in around substantial arcs of successive rotating work rolls with the unsupported length of strip between the rolls being a maximum of two inches and the ratio between strip width and unsupported length being at least 9 to 1, and applying tensional forces to the strip suflicient to stretch the strip between the rolls. Apparatus which may be used to practice the method includes two sets of bridle rolls having the rolls in one set driven at one speed equal to the speed of one work roll and the rolls in the other set driven at a different speed equal to the speed of the other work roll.

This invention relates to a method and apparatus for reducing strip thickness and more particularly for reducing cold steel strip to a very thin gauge. Strip is ordinarily reduced in thickness by a combination of compression and tension stresses, this being done in well known rolling mills. This has many disadvantages including the expensive and heavy equipment which is necessary because of the high roll pressures developed, the cost of providing cool'ants and lubricants, the high frictional horse power require-d to make the roll slip on the surface of the strip, and the restriction of the minimum strip thickness which is dependent upon the Work r011 diameter.

Stone Patent N0. 2,526,296 dated Oct. 17, 1950, discloses a method of reducing strip without the necessity of compression forces. However, the amount of reduction possible by Stones method and apparatus is limited to that for tension tempering which may be on the order of 3% as compared to reductions of many times that almount in cold rolling. Stones method also results in a necking down of the width of the strip.

It is therefore an object of my invention to provide a method of reducing strip gauge in which the width of the strip is not substantially reduced and by which large reductions may be made to very thin gauges.

Another object is to provide simple and relatively inexpensive apparatus for carrying out my method.

These and other objects will be more apparent after referring to the following specification and attached drawings, in which:

'FIGURE 1 is a schematic plan view of the apparatus of my invention;

FIGURE 2 is a schematic side elevation of the apparatus of FIGURE 1;

'FIGURE 3 is a longitudinal sectional view of a portion of the apparatus of my invention;

FIGURE 4 is a side elevation of a portion of FIGURE FIGURE 5 is a view taken on line V-V of FIGURE 4 on an enlarged scale; and

FIGURE 6 is a view taken on line V'IV'I of FIGURE Referring more particularly to the drawings, reference numeral 2 indicates a pay-off reel for suporting a coil of strip S. The reel 2 is connected through gear box 4 to a motor 6 which has a speed control 60. A stationary base '8 is arranged on the exit side of reel 2 and includes 4 3,377,830 lcfi Patented Apr. 16, 1968 spaced apart longitudinal ways 10 formed by a steel plate 12 and bronze plates 14, 1'6 and 18 attached thereto. A housing 20 is supported on the ways 10' for longitudinal sliding movement. The housing 20 includes at each longitudinal side a downwardly extending flange 22 with a horizontal plate 24 attached thereto. A longitudinal plate 26 is mounted on the base 8 along each side of the hou'sing 20 above the plate 24. At least two hydraulic cylinders 28 are mounted on the base 8 along each side of the housing 20. A piston rod 30 associated with each cylinder, extends upwardly from the base 8 and has a nut 32 threaded on its upper end. Slots 34 and 3 6 are provided in the plates 24 and 26, respectively for re ceiving each piston rod 30. A washer 38 is provided between the plate 26 and each nut 3-2. A reversible motor 40 is mounted on the base 8 and rotates a screw 42 through a gear reducer 44. A nut 46 attached to the bottom of housing 20 surrounds the screw 42 so that rotation of screw 42 will move the housing 20 longitu'dinally.

Bridle roll-s 4'8, 49, 50, 51, 52 and 53 and work roll '54 are rotatably suported in the housing 20. The work roll 54 preferably has a larger diameter than the bridle rolls. Rolls 48 to 54 are driven by motors 48M to 54M, respectively, through gearing 486 to 546 and shaft'in'g 485 to 548, respectively, the 'sh-a fting being so constructed that it permits movement of the housing 20 toward and away from a fixed housing 56. The motors 48M to 54M have individual speed controls 48C to 54C. Fixed housing 56 is arranged on the exit side of housing 20 and rotatably supports work roll 58 and bridle rolls 59, 60, 61, 62 and 63. It will be seen that work roll 58 is supported above work roll 54 and has substantially the same diameter as work roll 54. Rolls 58 to 63 are driven by motors 58M to 63M, respectively, through gearing 58G to 63G an d shafting 588 to 638. The motors 58M to 63M have individual speed controls 58C to 630. A winding reel 66 is mounted on the exit side of roll 63 and is driven train motor 68 through gearing 70. Motor 68 has a speed control 680. It will be seen that rolls 48 to 54 are arranged in staggered relationship and that the strip S passes around the rolls in a tortuous path with a sub- 'stantial amount of angular wrap developed by the strip being in contact with the surfaces of the rolls. This is also true of rolls 58 to 63. The speeds of the rolls 48 to 54 are controlled so that their peripheral speeds are equal. The peripheral speed of roll 58 is greater than the peripheral speed of roll 54 with the peripheral speeds of rolls 59 to 63 being equal to that of roll 58.

In preparing the line for operation, motor 40 is operated to move housing 20 away from housing 56 so that rolls 54 and 58 will be separated. While the amount of separation of these rolls may vary depending upon the width of the strip S, I have found that the unsupported length of the strip between these rolls must not exceed 2 in., and that this distance may be decreased to zero, but without any compression on the strip S. The unsupported length of strip is the distance from the point of tangency of the strip on roll 54 to the point of tangency of the strip on roll 58. I have also found that the ratio between the width of the strip and the unsupported length of the strip should be a minimum of 9 to 1 and is preferably greater. For example, a ratio of 36 to 1 gives good results. The speeds of the reel 2, rolls 48 to 54 and 58 to 63, and reel 66 are adjusted to give the desired reduction. After the housing 20 has been moved to its adjusted position, fluid is delivered to the upper part of the cylinders 28 so as to clamp the housing 20 in position against bronze block 14 and plate 26. After the strip S is threaded through the rolls from reel 2 and attached to winding reel 66, the rolls 48 to 54, 58 to 63 and the reels 2 and 66 are brought up to speed. The tension at roll 54 is built up to a value greater than the yield point but less than the ultimate strength of the strip and a matching tension is developed at roll 58. The tendency for the strip to strecth while in contact with rolls 54 and 58 is resisted by the frictional drag on these rolls. Also, the tendency for the strip to narrow while in contact with the roll .is. resisted by the frictioal drag. It will also be seen that roll 53 islocated so that a maximum wrap is provided .around roll 54 and roll 59 is positioned so that a maximum wrap is .provided around roll 58, this, of course, being desirable in order to obtain the maximum amount of frictional drag. It is only between the points of the beginning of the plastic state on roll 54 and the resumption of the elastic state on roll 58, including the space where the strip is unsupported, that reduction in thickness of the strip occurs and the shorter the unsupported length the greater the percent extension without substantial narowing of the strip.

While one embodiment of my invention has been shown and described, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

1. The method of reducing the thickness of a strip which comprises passing the strip continuously around substantial arcs of .first and secondrotating work rolls with the unsupported length of strip between the rolls being a maximum of two inches, and applying tensional forces to the strip so that the tension on the strip around at least part of the arc of wrap of .the work rolls is above its yield point but below its ultimate strength whereby the thickness of the strip is reduced as it passes between the work rolls.

2. The method of reducing the thickness of a strip according to claim 1 in which the ratio between the width of the strip and the unsupported length of strip is at least 9 to 1.

3. The method of reducing the thickness of a strip which comprises passing the strip continuously in a tortuous pass about a first set of driven bridle rolls,

driving the rolls at substantially the same peripheral velocities, then passing the strip about a substantial arc of a first work roll driven at substantially the same peripheral speed as the bridle rolls, then passing the strip about a substantial arc of a second work roll driven at a peripheral speed greater than the peripheral speed of the first work roll, spacing the first and second work rolls so that the unsupported length of strip is a maximum of two inches, passing the strip continuously in a tortuous pass about a second set of driven bridle rolls after it passes from the second work roll, driving rolls of said second set at substantially the same peripheral velocities as the second work roll, and regulating the relative speeds of all the rolls so that the tension on the strip around at least part of the arc of wrap of the work rolls is above its yield point but below its ultimate strength whereby the thickness of the strip is reduced as it passes between the work rolls.

4. The method of reducing the thickness of a strip according to claim 3 in which the ratio between the width of the strip and the unsupported length of strip is at least 9 to 1. I

5. Apparatusfor reducing the thickn ess of a strip comprising a first housing, a second housing, a plurality of bridle rolls rotatably mounted in said first housing around which the strip passes in a tortuous path, a work roll rotatably mounted in said first housing at the exit end thereof with the strip passing around a substantial arc thereof, means driving all of said rolls at substantially the same peripheral velocities, a second work roll rotatably mounted in said second housing adjacent the first Work roll, means rotating said second work roll at a peripheral speed greater than that of said first work roll, a plurality of bridle rolls rotatably mounted in said second housing around which the strip passes in a tortuous path, means'driving the last named bridle rolls at substantially the same peripheral velocity as the second work roll, means for moving one of said housings to and away from the other of said housings to change the distance between the work rolls, and means holding the movable housing from movement when the work rolls are spaced a desired distance apart.

6. Apparatus for reducing the thickness of a strip according to claim-5 in which the drive means for the rolls are electric motors and each motor has an individual speed control.

, References Cited 7 UNITED STATES PATENTS 2,526,296 10/ 1950 Stone 72-205 2,767,602 10/ 1956 Hendrickson 7223 7 3,253,445 5/1966 Franek 72164 CHARLES W. LANHAM, Primary Examiner. A. RUDERMAN, Assistant Examiner. 

